2013 年 69 巻 4 号 p. I_777-I_789
Estimation of dynamic characteristics of subsurface of ground such as predominant period, amplification factor, shear wave velocity play an important role in researchs of the effects of long-period ground motion earthquakes on high-rise buildings in big cities. Microtremor observations in Hanoi and HoChiMinh cities of Vietnam were conducted and the predominant period of the ground at the sites could be estimated from the horizontal to vertical (H/V) spectral ratios of microtremors by using the Nakamura method. The obtained results show that the grounds of the mentioned two cities have considerable possibility of resonance with long-period ground motions. Then, the spectral accelerations in bedrock of Hanoi and HoChiMinh cities were estimated by attenuation relationship of Uchiyama and Midorikawa 2006 with the far-source rupture faults. Next, the accelerations on ground surface of the above two Vietnamese cities were estimated by using spectral ratio of microtremor and inverse Fourier transform. Finally, the time history analysis was conducted for 8 high-rise buildings in Hanoi and HoChiMinh cities by using the obtained accelerations. The results of the final step show that far-source rupture faults have considerable possibility to generate long-period ground motions that cause certain large behaviors of high-rise buildings in the Vietnamese cities.
